Precision SC63/cast manifold/Tial 38mm wastegate, 2 1/2" DP, Vortech BOV.

when i ran my SC34 i could set boost at a rock-solid 15 psi with a home made boost controller.
i switched to the SC63 and it did the same. i take the car to get tuned. swap out my TurboSmart wastegate w/7psi spring for a Tial 38mm with 1BAR spring. boost would run up to about 15psi, then drop down to 13 or so.
i try two cheap boost controllers. with both we could get a peak of 22-23psi, but as soon as it would hit peak boost, it would drop down to about 18-19. it falls slightly slower than it rises.
put TurboSmart back on. set boost at 16 psi, but it drops down to 12-13. this all happens right around 5500 RPM.
i've tightned the BOV down a bit, checked all FMIC piping ( last time i had a leak it wouldn't hit peak boost at all, so i didn't think that was the problem).
i'm frusterated. here is my dyno chart. you can see where the dropping boost is killing me:



i'm about to pully my hair out not being able to figure this out...

if i were leaking boost, i'd never hit full boost, right? and if it were the wastegate, it would build boost then spike OVER the desired amount... correct? this sucks

oh, i also used to have my wastegate attatched directly to the exhaust manifold. i know use a 90-degree elbow. there are gaskets between mani/elbow as well as elbow/wastegate. since adding the elbow, i can now NOT use a dump tube. it just opens towards the top of the exhaust manifold, for now.

these are all the parts i've changed... grasping at straws..

 

anything from tuning, to ingition, to fueling. maybe you should give exact details of your setup.

 

have you ever tried an electronic boost controller and messing with the Gain values?

 

if you want boost values that high try a larger spring, i remember trying to run a steady 13 psi on my 7psi spring and it would fall off, then i swapped it over to a 1 bar spring and i had steady 13 all day long. also make sure your vacuum line to the boost controller is a short as you can make it, secondly try an electronic boost controller, i was having the same problem this year with boost dropping off until i swapped in my hks evc2 and i am having no more problems. Also maybe in the future try a larger 3" downpipe, 2.5 might be killing the flow of the turbo. good luck and keep us posted.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turbo_CRX &raquo;</TD></TR><TR><TD CLASS="quote">if you want boost values that high try a larger spring, i remember trying to run a steady 13 psi on my 7psi spring and it would fall off, then i swapped it over to a 1 bar spring and i had steady 13 all day long. also make sure your vacuum line to the boost controller is a short as you can make it, secondly try an electronic boost controller, i was having the same problem this year with boost dropping off until i swapped in my hks evc2 and i am having no more problems. Also maybe in the future try a larger 3" downpipe, 2.5 might be killing the flow of the turbo. good luck and keep us posted.</TD></TR></TABLE>

okay.. here's the deal:

car tuned by shawn church.
i used to run 15psi on my Turbosmart wastegate that has a 7psi spring. it held a SOLID 15psi when i'd use my home made boost controller.
i go to shawn's and remove the turbosmart. it was directly bolted to the exhaust manifold.
i had a 90-degree elbow in order to mount the Tial, which has a 1 BAR spring.
i boost 15psi, but it drops to 13. i then up the boost.
now, i boost 20 psi and it drops to 17-18.
i put the turbosmart back on. i try to run 18psi. it hits 18psi then drops to 16 or so.. well.. duh.. a 7psi spring won't hold 18psi.
tonight, i take off the elbow and put the turbosmart back on. it hit's 18psi then MUCH more slowly drops to 16psi or so. i figure THAT could be because the 7psi spring! but the car felt GREAT! so.. i have a 14psi spring to install in the turbosmart. i realize that it won't hold 18psi on the 7psi spring and that's why it's falling off NOW. i'm assuming putting the 14psi spring will solve that problem..

but as for before: with the tial..

could the elbow been the cause of the spiking??? everything worked great untill i added that elbow.

 

the elbow shouln't be the cause of the problem

 

check the bov, i've read about peeps that loose boost through those vortec ones

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RudeLude &raquo;</TD></TR><TR><TD CLASS="quote">check the bov, i've read about peeps that loose boost through those vortec ones</TD></TR></TABLE>

 

OT:

how high can a 7.25 psi spring go steady with an EBC?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SPOOLINmatt &raquo;</TD></TR><TR><TD CLASS="quote">OT:

how high can a 7.25 psi spring go steady with an EBC?</TD></TR></TABLE>

you shouldn't boost more than twice the amount of your spring. otherwise you will have problems, so i'm told.


so vortechs leak? should it work if i tighten it down all the way or are they just no good for high boost applications?? i'd hate to have to find another, though i DO have access to an RFL...

 

it may leak at higher boost, i know for sure the Blitz DD bov leaks at higher boost, thats why i upgraded to a Tial

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by eyustfu &raquo;</TD></TR><TR><TD CLASS="quote">it may leak at higher boost, i know for sure the Blitz DD bov leaks at higher boost, thats why i upgraded to a Tial</TD></TR></TABLE>

that would suck. i'm gonna go crank down the Vortech right now.

i'm assuming Vortech parts are meant for superchargers??? if so.. how many blowers put out 25psi of boost???!!!

 

update for anyone having the same problem i had. it appears to have been the BOV. i cranked it down all the way and it held boost @ 17psi ( on a 1 BAR spring...? ). i will keep messing with it so that it still holds boost while blowing off.
bottom line, i need a new BOV. i don't think this one is going to hold 25psi

 

those b.o.v. are meant for the vortec kits which blow out air all the time. a friend of mine had one on his super charged hatch and it blew out air at idle and closed when he got on it, but ive heard of them leaking on turbo cars

 

i recommend the Tial BOV's

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cubish &raquo;</TD></TR><TR><TD CLASS="quote">those b.o.v. are meant for the vortec kits which blow out air all the time. a friend of mine had one on his super charged hatch and it blew out air at idle and closed when he got on it, but ive heard of them leaking on turbo cars</TD></TR></TABLE>

i noticed that. the vaccum line at the top holds it open at idle. when you rev the engine it closes and stays closed.. well, unless you boost alot.
i have it adjusted to stay shut @ 17psi... i have yet to test it over 20psi. we'll see how it goes.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by eyustfu &raquo;</TD></TR><TR><TD CLASS="quote">i recommend the Tial BOV's</TD></TR></TABLE>

i have an RFL i'll use. it's a lot cheaper than buying a new BOV

 

OK guys a BOV opens when there is vacuum present, at idle vacuum is present, so you say " the vortech is open at idle and closes when you get on it"

uhh when is it not supposed to be that way?


OOPS old post

 

Is your wastegate dumping towards the inlet of the turbo or in that area? I have seen it several times where it was like that and as soon as the wastegate opened it would dump exhaust back into the turbo and would choke the turbo. I am willing to bet that is what you are dealing with.